Betaine copolymers with hydroxyalkylacrylates and hydroxyalkylmethacrylates

ABSTRACT

Copolymers of carboxybetaines or sulfobetaines having the formula WHEREIN R1 is hydrogen or methyl; A is oxygen or -NH-; R2 is ethylene, propylene, 2-hydroxypropylene or 2-acetoxypropylene; R3 and R4 are alkyl; n1 is 1 to 4 and X is SO3 or CO2 ; and about 10 to about 95.0 per cent by weight of hydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropylmethacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, polypropylene glycol acrylate, polypropylene glycol methacrylate, polyglycerolacrylate or polyglycerolmethacrylate are disclosed. These neutral, hydrophilic copolymers are useful as binders. This invention relates to selected copolymers comprising units derived from carboxybetaines or sulfobetaines and units derived from hydroxyalkyl acrylates/methacrylates, polyalkylene glycol acrylates/methacrylates or polyglycerol acrylates/methacrylates. More particularly, this invention relates to neutral, hydrophilic copolymers of monomers consisting essentially of about 5.0 to about 90 percent by weight of a carboxybetaine or sulfobetaine having the formula WHEREIN R1 is hydrogen or methyl; A is oxygen or -NH-; R2 is ethylene, propylene, 2-hydroxypropylene or 2-acetoxyproplene; R3 and R4 are alkyl; n1 is 1 to 4 and X is SO3 or CO2 ; and about 10 to about 95.0 per cent by weight of hydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropylmethacrylate, or a polyalkylene glycol acrylate/methacrylate or polyglycerol acrylate/methacrylate having the formula WHEREIN R&#39;&#39; is hydrogen or methyl, R&#39;&#39;&#39;&#39; is hydrogen, methyl or hydroxyl, n2 is zero where R&#39;&#39;&#39;&#39; is hydrogen or methyl and 1 where R&#39;&#39;&#39;&#39; is hydroxyl, and n3 is 2 to 4. Various carboxybetaines, sulfobetaines, homopolymers and copolymers thereof have been reported in the literature. Thus, U.S. Pat. Nos. 3,473,998 and 3,478,001 disclose sulfobetaines having the formula I and copolymers thereof with acrylonitrile, while U.S. Pat. No. 3,497,482 describes homopolymers of these sulfobetaines and copolymers with certain ethylenically unsaturated monomers. The carboxybetaines having the formula I, homopolymers thereof and copolymers with various ethylenically unsaturated compounds are reported in U.S. Pat. Nos. 2,777,872; 2,935,493 and 2,958,682. Now it has been found that copolymers of carboxybetaines and sulfobetaines with hydroxyalkylacrylates and hydroxyalkylmethacrylates can be provided according to this invention. These copolymers are particularly valuable as hydrophilic bonding agents for glass, leather, plastics, steel, hides and wood. The carboxybetaine and sulfobetaine monomers I can be conveniently prepared by reacting the appropriate Ndialkylaminoalkylacrylate/methacrylate or Ndialkylaminoalkylacrylamide/methacrylamide with a halomonocarboxylic (or sulfonic) acid salt or an alkyl lactone or sultone Following the procedure described in U.S. Pat. No. 2,744,130. Preparation of the copolymers of this invention is effected by polymerizing the carboxybetaine or sulfobetaine I or mixtures thereof, with hydroxyethylacrylate/methacrylate, hydroxypropylacrylate/methacrylate, polyethylene glycol acrylate/methacrylate, polypropylene glycol acrylate/methacrylate, polyglycerol acrylate/methacrylate, or mixtures thereof, the proportion of monomers being within the aforementioned range. The polymerization can be initiated by ultraviolet irradiation, heat, redox systems, peroxides, 2,2&#39;&#39;azobis-isobutyronitrile or other suitable means. Preferably, the polymerization is carried out in aqueous or organic solvent solutions at a temperature of from about room temperature to 100* C. Although any of the copolymers can be conveniently prepared, preferred copolymers are those of carboxybetaine or sulfobetaine I wherein R3 and R4 are alkyl having one to four carbon atoms with hydroxyethylacrylate/methacrylate or hydroxypropylacrylate/methacrylate. While not essential to the preparation of the copolymers of this invention, minor amounts, for example up to 10.0 percent by weight of the total monomer charge, of an appropriate crosslinking agent can be utilized. Thus, ethylene glycol dimethacrylate, polyethylene oxide dimethacrylate, N-methylol acrylamide, glycidyl methacrylate, etc. can be suitably employed as crosslinking agents. The copolymers of this invention are useful as hydrophilic binders for a variety of materials, having advantages for these applications over their respective homopolymers and over various copolymers of betaines with other ethylenically unsaturated monomers. Thus, for example, the adhesion of these copolymers to various substrates is better than that of the corresponding polysulfobetaine and polycarboxybetaine homopolymers. These copolymers have increased breaking strength over homopolymers of hydroxyalkylacrylates, thus rendering them highly attractive for use as binders in applications where strength is important, such as in the production of certain non-wovens.

United States Patent Samour et al.

[ 1 June 20, 1972 [54] BETAINE COPOLYMERS WITH HYDROXYALKYLACRYLATES ANDHYDROXYALKYLMETHACRYLATES [72] Inventors: Carlos M. Samour, Wellesley;Martin L.

Falxa, Cambridge, both of Mass.

[52] U.S.Cl ..260/79.3 MU, 117/122 P, 117/122 PF, 260/803 N, 260/80.73,260/86.1 N [51] Int. Cl ..C081 15/00,C08f 15/16 [58] Field of Search..260/79.3 M, 89.7 N, 89.5 N, 260/895 R, 86.1 N

[56] References Cited UNITED STATES PATENTS 2,833,650 5/1958 Shacklett..96/114 2,863,769 12/1958 Moede ..96/114 3,483,155 12/1969 Samour..260/29.6 3,509,111 4/1970 Samour ..260/78.5 R

Primary Examiner-Joseph L. Schofer Assistant Examiner-C. A. Henderson,Jr. AtlorneyEllen P. Trevors and Robert D. Chodera [5 7] ABSTRACTCopolymers of carboxybetaines or sulfobetaines having the formulawherein R, is hydrogen or methyl; A is oxygen or Nl-l; R is ethylene,propylene, 2-hydroxypropylene or 2-acetoxypropylene; R and R, are alkyl;n is l to 4 and X is S0,, or CO and about 10 to about 95.0 per cent byweight of hydroxyethylacrylate, hydroxyethylmethacrylate,hydroxypropylacrylate, hydroxypropylmethacrylate, polyethylene glycolacrylate, polyethylene glycol methacrylate, polypropylene glycolacrylate, polypropylene glycol methacrylate, polyglycerolacrylate orpolyglycerolmethacrylate are disclosed These neutral, hydrophiliccopolymers are useful as binders.

6 Claims, No Drawings BETAINE COPOLYMERS WITH HYDROXYALKYLACRYLATES ANDHYDROXYALKYLMETHACRYLATES This invention relates to selected copolymerscomprising units derived from carboxybetaines or sulfobetaines and unitsderived from hydroxyalkyl acrylates/methacrylates, polyalkylene glycolacrylates/methacrylates or polyglycerol acrylates/methacrylates.

More particularly, this invention relates to neutral, hydrophiliccopolymers of monomers consisting essentially of about 5.0 to about 90percent by weight of a carboxybetaine or sulfobetaine having the formulawherein R, is hydrogen or methyl; A is oxygen or NH; R is ethylene,propylene, 2-hydroxypropylene or 2-acetoxyproplene; R -and R are alkyl;n, is 1 to 4 and X is S; or CO and about to about 95.0 per cent byweight of hydroxyethylacrylate, hydroxyethylmethacrylate,hydroxypropylacrylate, hydroxypropylmethacrylate, or a polyalkyleneglycol acrylate/methacrylate or polyglycerol acrylate/methacrylatehaving the formula wherein R is hydrogen or methyl, R" is hydrogen,methyl or hydroxyl, n is zero where R" is hydrogen or methyl and l whereR" is hydroxyl, and n is 2 to 4.

Various carboxybetaines, sulfobetaines, homopolymers and copolymersthereof have been reported in the literature. Thus, U.S. Pat. Nos.3,473,998 and 3,478,001 disclose sulfobetaines having the formula 1 andcopolymers thereof with acrylonitrile, while US. Pat. No. 3,497,482describes homopolymers of these sulfobetaines and copolymers withcertain ethylenically unsaturated monomers. The carboxybetaines havingthe formula I, homopolymers thereof and copolymers with variousethylenically unsaturated compounds are reported in US. Pat. Nos.2,777,872; 2,935,493 and 2,958,682.

Now it has been found that copolymers of carboxybetaines andsulfobetaines with hydroxyalkylacrylates and hydroxyalkylmethacrylatescan be provided according to this invention.

These copolymers are particularly valuable as hydrophilic bonding agentsfor glass, leather, plastics, steel, hides and wood.

The carboxybetaine and sulfobetaine monomers I can be convenientlyprepared by reacting the appropriateN-dialkylaminoalkylacrylate/methacrylate orN-dialkylaminoalkylacrylamide/methacrylamide with a halomonocarboxylic(or sulfonic) acid salt or an alkyl lactone or sultone following theprocedure described in US. Pat. No. 2,744,130.

Preparation of the copolymers of this invention is effected bypolymerizing the carboxybetaine or sulfobetaine I or mixtures thereof,with hydroxyethylacrylate/methacrylate,hydroxypropylacrylate/methacrylate, polyethylene glycolacrylate/methacrylate, polypropylene glycol acrylate/methacrylate,polyglycerol acrylate/methacrylate, or mixtures thereof, the proportionof monomers being within the aforementioned range. The polymerizationcan be initiated by ultraviolet irradiation, heat, redox systems,peroxides, 2,2- azobis-isobutyronitrile or other suitable means.Preferably, the polymerization is carried out in aqueous or organicsolvent solutions at a temperature of from about room temperature toAlthough any of the copolymers can be conveniently prepared, preferredcopolymers are those of carboxybetaine or sulfobetaine 1 wherein R and Rare alkyl having one to four carbon atoms withhydroxyethylacrylate/methacrylate or hydroxypropylacrylate/methacrylate.

While not essential to the preparation of the copolymers of thisinvention, minor amounts, for example up to 10.0 percent by weight ofthe total monomer charge, of an appropriate crosslinking agent can beutilized. Thus, ethylene glycol dimethacrylate, polyethylene oxidedimethacrylate, N- methylol acrylamide, glycidyl methacrylate, etc. canbe suitably employed as crosslinking agents.

The copolymers of this invention are useful as hydrophilic binders for avariety of materials, having advantages for these applications overtheir respective homopolymers and over various copolymers of betaineswith other ethylenically unsaturated monomers. Thus, for example, theadhesion of these copolymers to various substrates is better than thatof the corresponding polysulfobetaine and polycarboxybetainehomopolymers. These copolymers have increased breaking strength overhomopolymers of hydroxyalkylacrylates, thus rendering them highlyattractive for use as binders in applications where strength isimportant, such as in the production of certain nonwovens.

The following examples will serve to illustrate the preparation ofvarious copolymers in accordance with the practice of this invention.

N-dimethylaminoethylmethacrylate (235.5 g.) was added slowly, withstirring, at 15 C to a mixture of y-propane sultone (183 g.) in ethylacetate (500 ml.). An exothermic reaction occurred. After completion ofthe addition, an additional ml. of ethyl acetate was added and thereaction mixture stirred for 4 hours at room temperature. The crudeproduct was separated from the reaction mixture by filtration, washedwith ethyl acetate and dried under vacuum at room temperature to provide150.6 g. of solid material. This solid product was dissolved in ml. ofhot methanol with stirring at room temperature. Then, ethyl acetate (400ml.) was added slowly, with stirring, to the clear solution. Thesolution was refrigerated overnight and crystals separated byfiltration. A second crop of crystals was obtained from the motherliquor by treatment with ethyl acetate followed by cooling. A totalyield of 140.0 g. of N-methacryloyloxyethyl-N,N-dimethyl-N,3-propyl-sulfobetaine was obtained, m.p. 280-300 C (dec).

B. Preparation of Copolymer A mixture of 9 g. of the sulfobetaineprepared in Part A, l g. of hydroxyethylmethacrylate and 0.02 ml. ofethylene glycol dimethylmethacrylate in 10 ml. of H,O prepared and 0.054g. potassium persulfate and 0.02 g. sodium bisulfite was added thereto.The resulting mixture was placed in a 13.5 cm X 4.2 cm X 0.4 cm cavityformed in a 15.7 cm X 4.5 cm X 1.3 cm polytetrafloroethylene piece. Thecavity was covered with a vented polytetrafloroethylene cover. Nitrogenwas passed over the mixture for about 2 hours; polymerization occurredovernight.

The breaking strength of the copolymer was determined according to thefollowing lap shear test procedure for both polyethylene terephthalateand steel substrates. After equilibration for 4-8 weeks in a 90 percenthumidity chamber, approximately 0.25 g. copolymer samples were placed onone end of duplicate 10 cm by 1.0 cm substrate strips. The polyethyleneterephthalate strips had a thickness of 4 mils; the steel strips, 2 milsthick. Each sample was pressed between release paper in a vise usingcalibrated metal spacers to a thickness of about 61.5 mils. After 15minutes, the substrate strips were removed from the vise and the samplestrimmed to a 1 cm by 1 cm area on the substrate. The samples werealigned with each other on opposite sides of a third strip comprised ofthe same material and having the same dimensions as the sample strips,and with the latter strips extending downwardly. Release paper wasplaced over the lapped assembly and the system placed in the vise andpressed to a thickness of 51.5 mils for 15 minutes. During all thepressing and trimming operations, the samples were held above a waterbath to maintain the 90 percent humidity environment. Then the assemblywas clamped in an Instron tester. Employing an Instron cross-head speedof 0.2 inch/min, the test was stopped when the shear stress peaked. Abreaking strength of 35.5 i 2.0 g./cm for polyethylene terephthalatesubstrate and 109.0 1 3.0 g./cm for steel were recorded.

EXAMPLE 2 Following the procedure of Example 1, Part B, a mixture of 0.5g. of the sulfobetaine prepared in Example 1, Part A and 9.5 g. ofhydroxyethylmethacrylate in 10 mlhof water was polymerized employing0.054 g. potassium persulfate and 0.02 g. sodium bisulfite .as theinitiator.

The breaking strength of the polymer was determined on an Instron Testeremploying a crosshead speed of 5 inches/min, a gauge length of 1 inch,and a sample 3 inches long, 0.210 inches wide and 0.122 inches thick.The breaking strength of the sample was 140 lb./sq. in.

EXAMPLE 3 A. Preparation of Carboxybetaine A mixture of YB-propiolactone (7.2 g.) in methyl ethyl ketone (10 g.) was addedslowly, with stirring, to a mixture of N-dimethylaminoethylmethacrylate(15.7 g.) and methyl ethyl ketone (10 g.). The reaction mixture wasmaintained at --1 to 30 C by means of a dry ice/acetone bath. Aftermaintaining the mixture at 0 C overnight, filtration provided 16 g. ofN-methacryloyloxyethyl-N,N-dimethyl-N,2-ethyl carboxybetaine, m.p.l02lOS C.

B. Preparation of Copolymer Following the procedure described in Examplel, Part B, a mixture of 9.5 g. of hydroxyethylmethacrylate and 0.5 g. ofthe carboxybetaine prepared in Part A in 10 ml. of water was polymerizedemploying 0.054 g. of potassium persulfate as the initiator. Thepolymerization was carried out overnight at 60 C.

EXAMPLE 4 The amount of 1.0 g. of the sulfobetaine prepared in Example lwas charged to a 20 ml. vial in an ice bath. The sulfobetaine wasdissolved in 5 ml. of water with stirring. To the solution was addedsequentially, with stirring, 1 ml. of ethanol, 9.0 g. ofhydroxpropylmethacrylate and 1.0 ml. of 3 percent hydrogen peroxidesolution. While continually stirring the solution, 0.5 ml. of anascorbic acid/ferrous catalyst, prepared by dissolving 0.02g. ferrousammonium sulphate and 0.4 g. ascorbic acid in ml. water, was addeddropwise. After 20 minutes, polymerization had occurred as evidenced bythe formation of a white, sticky mass when a drop of the reactionsolution was added to distilled water. The polymer solution was pouredinto a polyethylene terephthlate tray, which was placed in a vented ovenat 75 C for 2 hours in order to evaporate the solvents. The resultingpolymeric films were colorless and transparent.

EXAMPLE 5 A copolymer was prepared employing the reactants and followingthe procedure of Example 4, with the exception that 2.0 g. of thesulfobetaine were polymerized with 8.0 g. of hydroxpropylmethacrylate.

EXAMPLE 6 A copolymer was prepared employing the reactants and followingthe procedure of Example 4, with the exception that 3.0 g. of thesulfobetaine were polymerized with 7.0 g. of hydroxpropylmethacrylate.

COMPARATIVE EXAMPLE 1 For purposes of comparison, a homopolymer wasprepared by polymerizing 10 g. of the sulfobetaine described in Example1, Part A, in the presence of 0.02 ml. ethylene glycol dimethlacrylatein 10 ml. of water. Initiation was effected by the addition of 0.054 g.potassium persulphate and 0.02 g. sodium bisulfite. The polymerizationwas carried out in the same manner as described in Example 1.

Lap shear tests were carried out following the procedure described inExample 1, Part B. A breaking strength of 32.6 0.4 g./cm forpolyethylene terephthalate substrateand 85.0 t 1.5 g./cm for steel weredetermined. Since breaking strength is indicative of thepolymer-substrate bond, it will be apparent that the copolymer ofExample 1, prepared from percent by weight sulfobetaine and 10 percentby weight hydroxyethylmethacrylate, is a superior adhesive to thesulfobetaine homopolymer, its breaking strength being about 10 percentand 25 percent greater with respect to polyethylene terephthalate andsteel respectively, than that of the homopolymer.

COMPARATIVE EXAMPLE 2 For further purposes of comparison, a homopolymerof hydroxyethylmethacrylate was prepared from 10 g. ofhydroxyethylmethacrylate in 10 ml. of H 0 using the same initiatorsystem in the same amount and employing the polymerization techniquedescribed in Example 1. When a homopolymer sample 3 inches long, 0.180inches wide and 0.101 inches thick was tested in accordance with theprocedure described in Example 2, a breaking strength of lb./sq. in. wasrecorded.

What is claimed is:

l. A neutral, hydrophilic copolymer of monomers consisting essentiallyof a. about 5.0 to about 90 percent by weight of a carboxybetaine orsulfobetaine having the formula wherein R is hydrogen or methyl; A isoxygen or NH;

R is ethylene, propylene, 2-hydroxypropylene or 2- acetoxypropylene; Rand R are alkyl having one to four carbon atoms; n is l to 4 and X isS0] or CO] and b. about 10 to about 95.0 percent by weight ofhydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate,hydroxypropylmethacrylate, or a polyalkylene glycolacrylate/methacrylate or polyglycerol acrylate/methacrylate having theformula RI 0 RI! HzC= O(CH2-'C H"( 2)nf' '-)n wherein R is hydrogen ormethyl, R" is hydrogen, methyl or hydroxyl, n is zero where R" ishydrogen or methyl and l where R" is hydroxyl, and n is 2 to 4.

2. The copolymer of monomers of claim 1 consisting essentially of saidcarboxybetaine or said sulfobetaine with hydroxyethylacrylate,hydroxyethylmethacrylate, hydroxypropylacrylate orhydroxypropylmethoacrylat.

3. The copolymer of monomers of claim 2 wherein said carboxybetaine orsulfobetaine is selected from those having the formula of claim 1wherein R is ethylene and R and R are methyl.

4. The copolymer of monomers of claim 3 consisting essentially of about5.0 to about 90 percent by weight of N-methacryloyloxyethyhN,N-dimethyl-N,3-propyl-sulfobetaine and about 10 toabout 95.0 percent by weight hydroxyethylmethacrylate.

5. The copolymer of monomers of claim 3 consisting essentially of about5.0 to about 90 percent by weight of N-methacryioyloxyethyl-N,N-dimethyl-N,2-ethyl-carboxybetaine and about 10to about 95.0 percent by weight hydroxyethylmethacrylate.

and about 10 to about 95.0 percent by weight hydroxypropylmethacrylate.

2. The copolymer of monomers of claim 1 consisting essentially of saidcarboxybetaine or sAid sulfobetaine with hydroxyethylacrylate,hydroxyethylmethacrylate, hydroxypropylacrylate orhydroxyproplymethoacrylate.
 3. The copolymer of monomers of claim 2wherein said carboxybetaine or sulfobetaine is selected from thosehaving the formula of claim 1 wherein R2 is ethylene and R3 and R4 aremethyl.
 4. The copolymer of monomers of claim 3 consisting essentiallyof about 5.0 to about 90 percent by weight ofN-methacryloyloxyethyl-N,N-dimethyl-N,3-propyl-sulfobetaine and about 10to about 95.0 percent by weight hydroxyethylmethacrylate.
 5. Thecopolymer of monomers of claim 3 consisting essentially of about 5.0 toabout 90 percent by weight ofN-methacryloyloxyethyl-N,N-dimethyl-N,2-ethyl-carboxybetaine and about10 to about 95.0 percent by weight hydroxyethylmethacrylate.
 6. Thecopolymer of monomers of claim 3 consisting essentially of about 5.0 toabout 90 percent by weight ofN-methacryloyloxyethyl-N,N-dimethyl-N,3-propyl-sulfobetaine and about 10to about 95.0 percent by weight hydroxypropylmethacrylate.